Garmin uses a standard mini usb connector that you may already have from a camera.
$14 for Garmin Cable. I bought a 1GB Micro SD (SanDisk) for $35 after rebate locally. If you buy the Micro SD seperately, they come with a SD card carrier you can use to plug into the PC for map transfer. Don't waste money on a hi-speed card (They tend to have problems with GPS units).
For Biking Use, I don't see a big benefit with the vista. If you are into stats, the barometric altimeter on the Vista will show more accurate elevation changes in you active track log than the others.
The color etrex models come with the clip that attaches to the battery cover that latches into the rail mount. You still need to get/have the rail mount portion.
If you are near a Sportsmans Warehouse, they have the Venture CX for $220 during January (at least the mountain region's ad).